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Abstract:

A current detector includes a plurality of current paths arranged in
parallel, magnetic detection portions that are provided corresponding to
the plurality of current paths and have magnetic detection elements for
detecting strength of a magnetic field generated by an electric current
flowing through each of the current paths, a temperature sensor for
detecting a temperature of the magnetic detection portions, correction
circuits for correcting an output of the magnetic detection elements
based on a result of detection by the temperature sensor, and detection
circuits for detecting a magnitude of the electric current flowing
through each of the current paths based on the output corrected by the
correction circuits. The magnetic detection portions and the temperature
sensor are housed, together with a portion of the plurality of current
paths, in a molded package. A number of the temperature sensor is less
than that of the magnetic detection portions.

Claims:

1. A current detector, comprising: a plurality of current paths arranged
in parallel; magnetic detection portions that are provided corresponding
to the plurality of current paths and have magnetic detection elements
for detecting strength of a magnetic field generated by an electric
current flowing through each of the current paths; a temperature sensor
for detecting a temperature of the magnetic detection portions correction
circuits for correcting an output of the magnetic detection elements
based on a result of detection by the temperature sensor; and detection
circuits for detecting a magnitude of the electric current flowing
through each of the current paths based on the output corrected by the
correction circuits, wherein the magnetic detection portions and the
temperature sensor are housed, together with a portion of the plurality
of current paths, in a molded package, and wherein a number of the
temperature sensor is less than that of the magnetic detection portions.

2. The current detector according to claim 1, wherein the temperature
sensor is arranged at a position in the molded package where temperature
is substantially a median value of temperature distribution within an
installation region of the plurality of current paths.

3. The current detector according to claim 1, wherein the molded package
comprises a high-heat dissipation portion with a high thermal
conductivity and a low-heat dissipation portion with a lower thermal
conductivity than the high-heat dissipation portion, and wherein the
low-heat dissipation portion is disposed at an edge in an alignment
direction of the plurality of current paths.

4. The current detector according to claim 3, wherein the low-heat
dissipation portion is in filling fraction of a sealing material lower
than the high-heat dissipation portion.

5. The current detector according to claim 1, wherein the molded package
comprises a thermally conductive material housed in the molded package to
equalize a temperature inside the molded package.

6. The current detector according to claim 5, wherein the magnetic
detection portions and the temperature sensor are provided in contact
with the thermally conductive material.

7. The current detector according to claim 1, wherein a number of the
current paths is not less than three, and wherein the number of the
temperature sensor is not less than two and less than the number of the
magnetic detection portions.

8. A current detection method, comprising: providing magnetic detection
portions that are provided corresponding to a plurality of current paths
arranged in parallel and have magnetic detection elements for detecting
strength of a magnetic field generated by an electric current flowing
through each of the current paths; providing a temperature sensor for
detecting a temperature of the magnetic detection portions such that a
number of the temperature sensor is less than that of the magnetic
detection portions; housing the magnetic detection portions and the
temperature sensor together with a portion of the plurality of current
paths in a molded package; correcting an output of the magnetic detection
elements of not less than two of the magnetic detection portions based on
a result of detection by the temperature sensor; and detecting a
magnitude of the electric current flowing through each of the current
paths based on the corrected output.

9. The method according to claim 8, wherein the temperature sensor is
arranged at a position in the molded package where temperature is
substantially an intermediate value of temperature distribution within an
installation region of the plurality of current paths.

10. The method according to claim 8, wherein the molded package comprises
a high-heat dissipation portion with a high thermal conductivity and a
low-heat dissipation portion with a lower thermal conductivity than the
high-heat dissipation portion, and wherein the low-heat dissipation
portion is disposed at an edge in an alignment direction of the plurality
of current paths.

11. The method according to claim 10, wherein the low-heat dissipation
portion is in filling fraction of a sealing material lower than the
high-heat dissipation portion.

12. The method according to claim 8, wherein the molded package comprises
a thermally conductive material housed in the molded package to equalize
the temperature inside the molded package.

13. The method according to claim 12, wherein the magnetic detection
portions and the temperature sensor are provided in contact with the
thermally conductive material.

14. The method according to claim 8, wherein a number of the current
paths is not less than three, and wherein the number of the temperature
sensor is not less than two and less than the number of the magnetic
detection portions.

Description:

[0001] The present application is based on Japanese patent application No.
2014-238167 filed on Nov. 25, 2014, the entire contents of which are
incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to a current detector for detecting electric
current flowing through a current path by using a magnetic detection
element, and a current detection method.

[0004] 2. Description of the Related Art

[0005] For example, in the field of motor drive technology for hybrid and
electric vehicles etc., relatively large current is used and there is
thus a demand for current detectors capable of non-contact measurement of
high current. Some of such current detectors use a magnetic detection
element for detecting strength of a magnetic field generated by electric
current being measured, thereby detecting the magnitude of the electric
current being measured. The magnetic detection element can be a Hall
element using the Hall effect, an AMR element using the anisotropic
magnetoresistive (AMR) effect, a GMR element using the giant
magnetoresistive (GMR) effect or a TMR element using the tunnel
magnetoresistive (TMR) effect etc.

[0006] When an electric current flows through a current path, Joule heat
is generated in the current path and is transferred to the magnetic
detection element of which temperature thus changes. Since the output of
the magnetic detection element changes according to temperature, it is
necessary to detect the temperature by a temperature sensor and then to
correct the output of the magnetic detection element. Where the magnetic
detection element is a magnetoresistive effect element, a bias magnet of
the magnetoresistive effect element and a temperature sensor for
measuring temperature of the bias magnet are housed in a housing portion
and temperature characteristics of output signals of the magnetic
detection element are corrected based on output signals of the
temperature sensor (see, e.g., JP-A-2013-242301).

SUMMARY OF THE INVENTION

[0007] Where multiple current paths are arranged in parallel as in current
paths for supplying currents to a three-phase motor etc., the temperature
of the magnetic detection elements corresponding to the current paths is
difficult to accurately detect by single temperature sensor. In order to
accurately detect the temperature of each of the magnetic detection
elements to perform the accurate temperature correction, it is necessary
to provide a temperature sensor for each of the magnetic detection
elements corresponding to the current paths. Thus, the number of the
temperature sensors may increase so as to cause an increase in the cost
of the entire current detector.

[0008] It is an object of the invention to provide a current detector that
can make accurately the temperature correction even by using fewer
temperature sensor than before, as well as a current detection method.

(1) According to one embodiment of the invention, a current detector
comprises:

[0009] a plurality of current paths arranged in parallel;

[0010] magnetic detection portions that are provided corresponding to the
plurality of current paths and have magnetic detection elements for
detecting strength of a magnetic field generated by an electric current
flowing through each of the current paths;

[0011] a temperature sensor for detecting a temperature of the magnetic
detection portions;

[0012] correction circuits for correcting an output of the magnetic
detection elements based on a result of detection by the temperature
sensor; and

[0013] detection circuits for detecting a magnitude of the electric
current flowing through each of the current paths based on the output
corrected by the correction circuits,

[0014] wherein the magnetic detection portions and the temperature sensor
are housed, together with a portion of the plurality of current paths, in
a molded package, and wherein a number of the temperature sensor is less
than that of the magnetic detection portions.

(2) According to another embodiment of the invention, a current detection
method comprises:

[0015] providing magnetic detection portions that are provided
corresponding to a plurality of current paths arranged in parallel and
have magnetic detection elements for detecting strength of a magnetic
field generated by an electric current flowing through each of the
current paths;

[0016] providing a temperature sensor for detecting a temperature of the
magnetic detection portions such that a number of the temperature sensor
is less than that of the magnetic detection portions;

[0017] housing the magnetic detection portions and the temperature sensor
together with a portion of the plurality of current paths in a molded
package;

[0018] correcting an output of the magnetic detection elements of not less
than two of the magnetic detection portions based on a result of
detection by the temperature sensor; and

[0019] detecting a magnitude of the electric current flowing through each
of the current paths based on the corrected output.

Effects of the Invention

[0020] According to one embodiment of the invention, a current detector
can be provided that can make accurately the temperature correction even
by using fewer temperature sensor than before so as to decrease the cost
of the entire current detector, as well as a current detection method.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Next, the present invention will be explained in more detail in
conjunction with appended drawings, wherein:

[0022] FIG. 1 is an illustration diagram showing a configuration of
magnetic detection portions of current detectors in embodiments of the
present invention;

[0023] FIG. 2A is a perspective view showing a current detector in a first
embodiment of the invention;

[0024] FIG. 2B is a cross sectional view taken along a line A-A in FIG.
2A;

[0025] FIG. 3 is an illustration diagram showing an example of temperature
distribution in a molded package;

[0026] FIG. 4A is a perspective view showing a current detector in a
second embodiment of the invention;

[0027] FIG. 4B is a cross sectional view taken along a line B-B in FIG.
4A;

[0028] FIG. 5A is a perspective view showing a current detector in a third
embodiment of the invention;

[0029] FIG. 5B is a cross sectional view taken along a line C-C in FIG.
5A;

[0030] FIG. 6A is a perspective view showing a current detector in a
fourth embodiment of the invention; and

[0031] FIG. 6B is a cross sectional view taken along a line D-D in FIG.
6A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Configuration of Magnetic Detection Portion

[0032] FIG. 1 is an illustration diagram showing a configuration of
magnetic detection portions of current detectors in the embodiments of
the invention. Magnetic detection portions 11 to 13 of the current
detector have a half-bridge configuration with magnetic detection
elements 15 and 16. Each of the magnetic detection elements 15 and 16 is
constructed from a GMR element and detects strength of a magnetic field
generated by an electric current flowing through a current path.

[0033] The GMR element has a higher sensitivity than the Hall element. In
more detail, while the minimum detectable magnetic field of the Hall
element is 0.5 Oe (0.05 mT in terms of magnetic flux density in the air),
that of the GMR element is 0.02 Oe (0.002 mT in terms of magnetic flux
density in the air). In addition, the response speed of the GMR element
is faster than other magnetic detection elements such as the Hall
element. Furthermore, unlike, e.g., a coil, etc., which senses a change
in a magnetic field, the GMR element directly detects the magnetic field
itself and thus can be highly responsive to even a very small change in
the magnetic field. Therefore, use of the GMR element as the magnetic
detection elements 15 and 16 improves accuracy of detecting a magnetic
field generated by an electric current flowing through a current path.

[0034] The magnetic detection elements 15 and 16 are connected in series
and are arranged so that magnetosensitive axis directions indicated by
arrows are opposite to each other. A driving voltage +Vcc/2 is applied to
a terminal on the magnetic detection element 15 side and a driving
voltage -Vcc/2 is applied to a terminal on the magnetic detection element
16 side. Then, outputs signals are output from a junction between the
magnetic detection elements 15 and 16. A correction circuit 17 performs
temperature correction of the output signals based on a result of
detection by a temperature sensor 14. A detection circuit 18 detects the
magnitude of the electric current flowing through the current path based
on the output signals corrected by the correction circuit 17.

[0035] The magnetic detection elements 15 and 16 and the correction
circuit 17 are arranged on one chip. Alternatively, the magnetic
detection elements 15 and 16 may be arranged on separate chips. As
another alternative, the correction circuit 17 may be provided outside
the chip. Or, the detection circuit 18 may be arranged on the chip.

[0036] Although a bias coil for generating a bias magnetic field to be
applied to the GMR element is provided on each of the magnetic detection
portions 11 to 13, the illustration of the bias coil is omitted in FIG.
1. The magnetic detection portions 11 to 13 may alternatively have a
full-bridge configuration with four magnetic detection elements.

First Embodiment

[0037] FIG. 2A is a perspective view showing a current detector in the
first embodiment of the invention. In FIG. 2A, three current paths 1 to 3
are three-phase current paths and are arranged in parallel. Each of the
current paths 1 to 3 corresponds to any one of three phases U, V and W.
Each of the current paths 1 to 3 is a plate shaped busbar of which width
direction coincides with an alignment direction of the current paths 1 to
3. The width direction of the busbar may be orthogonal to the alignment
direction of the current paths 1 to 3.

[0038] A molded package 20 is provided on the current paths 1 to 3 so as
to house a portion of the current paths 1 to 3. For a sealing material
constituting the molded package 20, a highly thermally conductive
material among heat resistant resins such as epoxy resin or ceramic
materials such as alumina is used. A material with improved thermal
conductivity obtained by, e.g., modifying a molecular structure of a
conventional sealing material or by mixing a base resin such as
polycarbonate with a filler as an additive may alternatively be used.

[0039] FIG. 2B is a cross sectional view taken along a line A-A in FIG.
2A. The magnetic detection portions 11 to 13 respectively corresponding
to the current paths 1 to 3 are provided in the molded package 20. The
magnetic detection portion 11 detects strength of a magnetic field
generated by an electric current flowing through the corresponding
current path 1. The magnetic detection portion 12 detects strength of a
magnetic field generated by an electric current flowing through the
corresponding current path 2. The magnetic detection portion 13 detects
strength of a magnetic field generated by an electric current flowing
through the corresponding current path 3.

[0040] The magnetic detection portions 11 to 13 are housed together with a
portion of the current paths 1 to 3 in the molded package 20. Therefore,
heat generated by the current paths 1 to 3 is transferred to the sealing
material of the molded package 20, the temperature inside the molded
package 20 becomes substantially uniform and a temperature difference
between the magnetic detection portions 11 to 13 is reduced.

[0041] The temperature sensor 14 is provided inside the molded package 20.
In the first embodiment, the temperature sensor 14 is shared among the
magnetic detection portions 11 to 13 and is arranged at the same height
as that of the magnetic detection portions 11 to 13. The respective
correction circuits 17 of the magnetic detection portions 11 to 13
correct the outputs of the magnetic detection elements 15 and 16 of the
magnetic detection portions 11 to 13 based on a result of detection by
one temperature sensor 14. The temperatures of the magnetic detection
portions 11 to 13 are accurately detected by only one temperature sensors
14 (few in number), and temperature correction is performed highly
accurately.

[0042] FIG. 3 is an illustration diagram showing an example of temperature
distribution in the molded package. In FIG. 3, the horizontal axis
indicates a distance from a position on the line passing through the
center of the current path 2 illustrated by a dotted line to positions
away therefrom in the alignment direction of the current paths 1 to 3,
and the vertical axis indicates temperature at a predetermined height on
the upper or lower side of the current paths 1 to 3. The temperature
inside the molded package 20 is highest at the position on the line
passing through the center of the current path 2 and gradually decreases
with increasing the distance from the center of the current path 2. Then,
the temperature decreases largely out of the installation region of the
current paths 1 to 3 (beyond the left edge of the current path 1
illustrated by a dotted line and beyond the right edge of the current
path 3 illustrated by a dotted line in FIG. 3). When the maximum value of
the temperature within the installation region of the current paths 1 to
3 is Tmax, the minimum value is Tmin and the median value is Ta, the
temperature sensor 14 is arranged at a position in the molded package 20
where temperature is substantially the median value Ta of temperature
distribution within the installation region of the plural current paths 1
to 3.

[0043] In the first embodiment in which the three current paths are
provided, the position at which temperature is the median value Ta is a
position shifted to the current path 1 side from the center between the
current paths 1 and 2, and also a position shifted to the current path 3
side from the center between the current paths 2 and 3.

[0044] Since the temperature sensor 14 is arranged at a position in the
molded package 20 where temperature is substantially the median value of
temperature distribution within the installation region of the plural
current paths 1 to 3, a difference between the temperature detected by
the temperature sensor 14 and the actual temperature of each of the
magnetic detection portions 11 to 13 is reduced.

Functions and Effects of the First Embodiment

[0045] The following functions and effects are obtained in the first
embodiment.

[0046] (1) The magnetic detection portions 11 to 13 and the
temperature sensor 14 are housed together with a portion of the plural
current paths 1 to 3 and the number of the temperature sensors 14
provided is smaller than the number of the magnetic detection portions 11
to 13. In this configuration, only a few temperature sensors 14 can
accurately detect the temperatures of the magnetic detection portions 11
to 13, thereby allowing for highly accurate temperature correction.
Therefore, it is possible to highly accurately detect the magnetic fields
generated by the electric currents flowing through the current paths 1 to
3 and thereby to accurately detect the electric currents flowing through
the current paths 1 to 3, while reducing the cost of the detector.

[0047] (2) By arranging the temperature sensor 14 at a position in the
molded package 20 where temperature is substantially the median value of
temperature distribution within the installation region of the plural
current paths 1 to 3, it is possible to reduce detection errors, thereby
allowing for more highly accurate temperature correction.

Second Embodiment

[0048] FIG. 4A is a perspective view showing a current detector in the
second embodiment of the invention. A molded package 21 in the second
embodiment has a high-heat dissipation portion 22 having a high thermal
conductivity and low-heat dissipation portions 23 having a lower thermal
conductivity than the high-heat dissipation portion 22. The remaining
configuration is the same as the first embodiment shown in FIG. 2A.

[0049] In the high-heat dissipation portion 22, a sealing material is
filled substantially without voids. The low-heat dissipation portion 23
has, e.g., a honeycomb structure in which the sealing material has
hollows. Due to the difference in the filling fraction of the sealing
material, the low-heat dissipation portion 23 has a lower thermal
conductivity than the high-heat dissipation portion 22.

[0050] Alternatively, the high-heat dissipation portion 22 and the
low-heat dissipation portion 23 may be formed of materials having
different thermal conductivities.

[0051] FIG. 4B is a cross sectional view taken along a line B-B in FIG.
4A. In the molded package 21, the low-heat dissipation portions 23 are
provided at the edges in the alignment direction of the plural current
paths 1 to 3. When a portion of the current paths 1 to 3 arranged in
parallel is housed in the molded package 21, the temperature distributed
in the molded package 21 is highest at the center in the alignment
direction of the current paths 1 to 3 and is slightly lower at the edges.
By configuring the low-heat dissipation portions 23 having a lower
thermal conductivity than the high-heat dissipation portion 22 to be
provided at the edges in the alignment direction of the plural current
paths 1 to 3, the heat-dissipation effect is lower at the edges provide
with the low-heat dissipation portions 23 than in the high-heat
dissipation portion 22 and the temperature inside the molded package 21
becomes more uniform.

Functions and Effects of the Second Embodiment

[0052] The second embodiment achieves the same functions and effects as
(1) and (2) described for the first embodiment.

[0053] Furthermore, by configuring the low-heat dissipation portions 23
having a lower thermal conductivity than the high-heat dissipation
portion 22 having a high thermal conductivity to be provided at the edges
of the molded package 21 in the alignment direction of the plural current
paths 1 to 3, it is possible to further equalize the temperature inside
the molded package 21.

[0054] In addition, by configuring the low-heat dissipation portion 23 so
that the filling fraction of the sealing material thereof is lower than
that of the high-heat dissipation portion 22, it is possible to use the
same material to form the high-heat dissipation portion 22 and the
low-heat dissipation portion 23.

Third Embodiment

[0055] FIG. 5A is a perspective view showing a current detector in the
third embodiment of the invention. In the third embodiment, a thermally
conductive material 25 to equalize temperature inside a molded package 24
is housed in the molded package 24. The remaining configuration is the
same as the first embodiment shown in FIG. 2A. Alternatively, the
thermally conductive material 25 may be housed in the molded package 21
in the second embodiment shown in FIG. 4A.

[0056] The thermally conductive material 25 is formed of a material having
a higher thermal conductivity than a sealing material of the molded
package 24. Good moldability is required for the sealing material of the
molded package 24 but is not required for a material of the thermally
conductive material 25 which only needs to have a plate shape, a foil
shape or a rod shape, etc. Therefore, it is possible to use various
highly thermally conductive materials to form the thermally conductive
material 25.

[0057] In detail, the thermally conductive material 25 may be, e.g., a
metal such as an aluminum sheet, a copper sheet, an aluminum foil and a
copper foil. In case that the thermally conductive material 25 is an
electrical conductor, the magnetic detection portions 11 to 13 and the
temperature sensor 14 each have an electrode on a surface other than the
surface in contact with the thermally conductive material 25.
Alternatively, a substrate having a circuit pattern may be used as the
thermally conductive material 25, such that electrodes of the elements
constituting the magnetic detection portions 11 to 13 and the temperature
sensor 14, etc., are connected to the circuit pattern (in this case, the
magnetic detection portions 11 to 13 and the temperature sensor 14, etc.,
may have the electrodes on any surfaces). Additionally, in this case, the
circuit pattern connected to the electrodes of the elements constituting
the magnetic detection portions 11 to 13 and the temperature sensor 14,
etc., may be exposed from the molded package.

[0058] FIG. 5B is a cross sectional view taken along a line C-C in FIG.
5A. In the molded package 24, the thermally conductive material 25 is
placed along the alignment direction of the plural current paths 1 to 3.
The temperature inside the molded package 24 in the alignment direction
of the plural current paths 1 to 3 is further equalized by the thermally
conductive material 25.

[0059] In the third embodiment, the magnetic detection portions 11 to 13
and the temperature sensor 14 are provided in contact with the thermally
conductive material 25. Thus, the temperature of each of the magnetic
detection portions 11 to 13 becomes substantially the same as the
temperature of the thermally conductive material 25, resulting in that a
difference between the temperature detected by the temperature sensor 14
and the actual temperature of each of the magnetic detection portions 11
to 13 is further reduced.

Functions and Effects of the Third Embodiment

[0060] The third embodiment achieves the same functions and effects as (1)
and (2) described for the first embodiment.

[0061] In addition, by housing the thermally conductive material 25 in the
molded package 24, it is possible to further equalize the temperature
inside the molded package 24.

[0062] Furthermore, by providing the magnetic detection portions 11 to 13
and the temperature sensor 14 so as to be in contact with the thermally
conductive material 25, it is possible to further reduce the difference
between the temperature detected by the temperature sensor 14 and the
actual temperature of each of the magnetic detection portions 11 to 13.

Fourth Embodiment

[0063] FIG. 6A is a perspective view showing a current detector in the
fourth embodiment of the invention and FIG. 6B is a cross sectional view
taken along a line D-D in FIG. 6A. In the fourth embodiment, plural
temperature sensors 14 are housed in the molded package 20. The remaining
configuration is the same as the first embodiment shown in FIG. 2A.
Alternatively, the plural temperature sensors 14 may be housed in the
molded package 21 in the second embodiment shown in FIG. 4A, or may be
housed in the molded package 24 in the third embodiment shown in FIG. 5A.

[0064] In the fourth embodiment, two temperature sensors 14, which are
fewer than the magnetic detection portions 11 to 13, are arranged at
symmetrical positions with the current path 2 interposed therebetween.
The temperature sensors 14 are located at the positions, indicated by
dotted lines in FIG. 3, in the molded package 20 where temperature is
substantially the median value Ta of temperature distribution within the
installation region of the plural current paths 1 to 3.

[0065] During the normal operation, temperature correction of the outputs
of the magnetic detection elements 15 and 16 of the magnetic detection
portions 11 to 13 is performed based on the average of the outputs of the
two temperature sensors 14. The temperature of each of the magnetic
detection portions 11 to 13 is detected more accurately, and temperature
correction is performed more highly accurately. Meanwhile, when one of
the temperature sensors 14 fails, the output of the other non-faulty
temperature sensor 14 is used for temperature correction of the outputs
of the magnetic detection elements 15 and 16 of the magnetic detection
portions 11 to 13.

Functions and Effects of the Fourth Embodiment

[0066] The fourth embodiment achieves the same functions and effects as
(1) and (2) described for the first embodiment.

[0067] In addition, plural temperature sensors 14 are housed in the molded
package 20. Therefore, even when some of the plural temperature sensors
14 fail, it is possible to perform temperature correction of the outputs
of the magnetic detection elements 15 and 16 of the magnetic detection
portions 11 to 13 by using the outputs of the non-faulty temperature
sensors 14. In addition, the temperature correction of the outputs of the
magnetic detection elements 15 and 16 of the magnetic detection portions
11 to 13 based on the average of the outputs of the plural temperature
sensors 14 allows for more highly accurate temperature correction.

SUMMARY OF THE EMBODIMENTS

[0068] Technical ideas understood from the embodiments will be described
below citing the reference numerals, etc., used for the embodiments.
However, each reference numeral described below is not intended to limit
the constituent elements in the claims to the members, etc., specifically
described in the embodiments.

[0069] [1] A current detector, comprising: a plurality of current paths
(1, 2, 3) arranged in parallel; magnetic detection portions (11, 12, 13)
that are provided to respectively correspond to the current paths (1, 2,
3) and each have magnetic detection elements (15, 16) for detecting
strength of a magnetic field generated by an electric current flowing
through each current path (1, 2, 3); a temperature sensor(s) (14) for
detecting temperatures of the magnetic detection portions (11, 12, 13);
correction circuits (17) for correcting outputs of the magnetic detection
elements (15, 16) based on a result of detection by the temperature
sensor(s) (14); and detection circuits (18) for detecting the respective
magnitudes of the electric currents flowing through the current paths (1,
2, 3) based on the outputs corrected by the correction circuits (17),
wherein the magnetic detection portions (11, 12, 13) and the temperature
sensor(s) (14) are housed, together with a portion of the plurality of
current paths (1, 2, 3), in a molded package (20/21/24), and the number
of the temperature sensors (14) provided is smaller than the number of
the magnetic detection portions (11, 12, 13).

[0070] [2] The current detector, wherein the temperature sensor(s) (14) is
arranged at a position in the molded package (20/21/24) where temperature
is substantially the median value of temperature distribution within an
installation region of the plurality of current paths (1, 2, 3).

[0071] [3] The current detector, wherein the molded package (21) comprises
a high-heat dissipation portion (22) having a high thermal conductivity
and low-heat dissipation portions (23) that have a lower thermal
conductivity than the high-heat dissipation portion (22) and are located
at edges in an alignment direction of the plurality of current paths (1,
2, 3).

[0072] [4] The current detector, wherein the low-heat dissipation portion
(23) is configured that a filling fraction of a sealing material thereof
is lower than that of the high-heat dissipation portion (22).

[0073] [5] The current detector, wherein a thermally conductive material
(25) to equalize the temperature inside the molded package (24) is housed
in the molded package (24).

[0074] [6] The current detector, wherein the magnetic detection portions
(11, 12, 13) and the temperature sensor(s) (14) are provided in contact
with the thermally conductive material (25).

[0075] [7] The current detector, wherein the number of the current paths
(1, 2, 3) provided is not less than three, and the number of the
temperature sensors (14) provided is not less than two but smaller than
the number of the magnetic detection portions (11, 12, 13).

[0076] [8] A current detection method, comprising: providing magnetic
detection portions (11, 12, 13) that are provided to correspond to a
plurality of current paths (1, 2, 3) arranged in parallel and each have
magnetic detection elements (15, 16) for detecting strength of a magnetic
field generated by an electric current flowing through each current path
(1, 2, 3); providing a temperature sensor(s) (14) for detecting
temperatures of the magnetic detection portions (11, 12, 13) so that the
number of the temperature sensors (14) is smaller than the number of the
magnetic detection portions (11, 12, 13); housing the magnetic detection
portions (11, 12, 13) and the temperature sensor(s) (14) together with a
portion of the plurality of current paths (1, 2, 3) in a molded package
(20/21/24); correcting outputs of the magnetic detection elements (15,
16) of not less than two of the magnetic detection portions (11, 12, 13)
based on a result of detection by the one temperature sensor (14); and
detecting the magnitude of the electric current flowing through each
current path (1, 2, 3) based on the corrected outputs.

[0077] [9] The method, wherein the temperature sensor(s) (14) is arranged
at a position in the molded package (20/21/24) where temperature is
substantially the intermediate value of temperature distribution within
an installation region of the plurality of current paths (1, 2, 3).

[0078] [10] The method, wherein a high-heat dissipation portion (22)
having a high thermal conductivity and low-heat dissipation portions (23)
having a lower thermal conductivity than the high-heat dissipation
portion (22) are provide in the molded package (21), and the low-heat
dissipation portions (23) are located at edges of the molded package (21)
in an alignment direction of the plurality of current paths (1, 2, 3).

[0079] [11] The method, wherein the low-heat dissipation portion (23) is
configured that a filling fraction of a sealing material thereof is lower
than that of the high-heat dissipation portion (22).

[0080] [12] The method, wherein a thermally conductive material (25) is
housed in the molded package (24) to equalize the temperature inside the
molded package (24).

[0082] [14] The method, wherein the number of the current paths (1, 2, 3)
provided is not less than three, and the number of the temperature
sensors (14) provided is not less than two but smaller than the number of
the magnetic detection portions (11, 12, 13).

[0083] Although the embodiments of the invention have been described, the
invention according to claims is not to be limited to the embodiments.
Further, please note that all combinations of the features described in
the embodiments are not necessary to solve the problem of the invention.

[0084] The invention can be appropriately modified and implemented without
departing from the gist thereof. For example, although the GMR elements
are used as the magnetic detection elements 15 and 16 in the embodiments,
other magnetic detection elements such as Hall elements, AMR elements or
TMR elements may be used.

[0085] In addition, although three current paths 1 to 3 are provided in
the embodiments, the number of the current paths is not limited thereto
and may be two or not less than four. The number of the temperature
sensors 14 is also not limited to one or two as long as fewer than the
magnetic detection portions (the same number as the current paths).